This invention relates generally to improvements in operating an illuminated electroptic display for a multimode or multifunction wristwatch. More particularly, it relates to an improved logic sequence for a wristwatch with multiple manual switch actuators and provisions for illuminating the dial or display of the wristwatch.
Means for illuminating wristwatch dials or liquid crystals displays which could otherwise not be seen in the dark are well known. The illuminating lamps may be incandescent lamps arranged to serve as a backlight for a liquid crystal display as shown in U.S. Pat. No. 4,342,105--Dorfman. Other types of backlighting lamps, such as electroluminescent lamps, have also been used in watches, as shown in U.S. Pat. No. 4,500,173--Leibowitz et al.
Generally, the lamp illuminating the display or dial is lit by pressing a pushbutton to close contacts inside the watchcase so as to change the electrical potential on an integrated circuit input pin, signifying a switch closure.
In actual practice, the manual actuator may either be a dedicated switch which only serves to light the illuminating lamp, or the switch may incidentally cause the lamp to light while some other function is being performed with the switch. Electronic watches are also known, in which various special lighting functions or timing functions are performed when the manual actuators are operated in a preselected manner. U.S. Pat. No. 4,084,401--Belardi et al describes a digital LED display watch, in which an additional recessed button is provided to manually select the duty cycle of the display and thus alter apparent brightness and power consumed. U.S. Pat. No. 4,094,139--Nomura et a describes a display control circuit for an electronic timepiece for controlling a timer circuit to vary the length of time for the display of time or calendar information. U.S. Pat. No. 4,033,108--Bennett et al describes an LED electronic watch, in which the display is quiescent to conserve power, by providing an automatic cut-off system to discontinue the display immediately after the time is displayed.
Multimode, multifunction wristwatches (or wrist instruments) are known which include a display, a lamp for illuminating the display, a number of manually actuated switches and an integrated circuit programmed in a preselected sequence. Examples of such watches are seen in U.S. Pat. No. 4,783,773--Houlihan et al, U.S. Pat. No. 4,780,864--Houlihan and U.S. Pat. No. 4,283,784--Horan, all of the foregoing being assigned to the present assignee. In the foregoing patents, which are merely exemplary of multimode electronic wrist instruments or multifunction wristwatches, one of the manual actuators may typically serve to repetitively cycle the instrument through a number of modes or operating states in each of which a different type of information is displayed. Such modes may include, in a multifunction watch, the time of day, chronograph, dual time zone, elapsed time and so forth. By special preselected actuation of one of the switches, the wristwatch may b further converted into a computer, a speedometer, pulsometer or any other type of device, subject only to the imagination of the designer and programmer of the integrated circuit. While in any of these modes, another manual switch actuator may be employed to change the information being displayed in that mode or state, such as initiating the chronograph timing or setting the time-of-day, or performing a calculation.
A common problem occurring with the multimode electronic wristwatch or wrist instrument described above is that a change of mode or a change of information displayed within a mode may not be observed in the night or under poor light conditions without also pressing the manual actuator for illuminating the display. If a series of such activities are to be performed in conditions of little or no ambient light then this calls for repetitive actuation of the illuminating pushbutton. On the other hand, considerations of power and battery conservation would not allow the illuminating lamp to remain lighted at all times.
Accordingly, one object of the present invention is to provide an improved method of controlling the illumination of the display in a multimode electronic wristwatch.
Still another object of the invention is to provide an improved means for operating an electronic wristwatch to provide automatic illumination of the display while also conserving power.